1. Field of the Invention
The present invention relates to a vehicle steering apparatus capable of changing a transmission ratio of the steering angle of a steering wheel to the turning angle-of a tire.
2. Related Background Art
A steering apparatus disclosed in Japanese Patent Laid-Open No. 3-153467 is available as a conventional steering apparatus capable of changing the transmission ratio of the steering angle of the steering wheel to the turning angle of the tire. This steering apparatus comprises a transmission ratio change mechanism constituted by a planetary gear differential mechanism mounted on a steering shaft between a steering wheel and a pinion connected to a tire.
The transmission ratio change mechanism of this steering apparatus is of a differential type. For this reason, when an excessive load such as an excessive reverse input from a vehicle wheel or tire during traveling acts on the transmission ratio change mechanism, the transmission ratio change mechanism is moved by this load to change the relationship between the steering amount of the steering wheel and the turning amount of the tire.